Alexander Duncan married Isobel Crawford, 26 August 1736 in Dundee.
I am hoping to find burial records/MI which would (hopefully) give some indication of Isobel's date of birth. One source I have found indicates that Isobel was born c 1811 the daughter of Henry Crawford of Monorgan and Ann Hay. This indicates that Isobel married at the age of 25.

I have found an Isabella Crawford born 1720 and the daughter of Henry Crawford of Monorgan and Elizabeth Paton.

If this is the spouse of Alexander Duncan then she married at the age of 16

I have not been able to locate Isobel Crawford born c 1711.
The last child I have for Alexander Duncan and Isobel Crawford is 1754 born in Dundee.

Any assistance appreciated